Polarity reversing distributor



June 25, 1946. H, D ET AL 2,402,543

POLARITY REVERSING DISTRIBUTOR Filed May 17, 1943 2 Sheets-Sheet l l8 I I lE-Z HenryForcl E Eu 2 Emil Z 0er1e1'n INVENTOR. BY {34 (W June 25, 1946. H. FORD ETAL 2,402,543

POLARITY REVERSING DISTRIBUTOR Filed May 17, 1943 2 Sheets-Sheet 2 i 21" E Q/W Patented June 25, 1946 UNITED STATES PATENT OFFICE Henry Ford and Emil Zoerlein, Deal-born, Mich, assignors to Ford Motor Company, Dearborn, Mich, a corporation of Delaware Application May 17, 1943, Serial No. 487,376

3. Claims. (Cl. 200-30) This invention relates to a distributor for use with multicylinder, internal-combustion engine; and, more particularly, to a distributor in which provision is made for the reversing of the polarity of the breaker points at each operation thereof.

The desirability of making some provision for automatic reversal of the polarity at the breaker points of ignition devices in internal-combustion engines has been recognized. This flows principally from the fact that when polarity of the points remains constant, the metal is continuously transferred from one point to the other and imbedded inclusions of oxide or foreign matter seriously reduce the efficiency of the contact. Devices have .been used in which the reversal of polarity, rather than taking place at each operation of the breaker arm, takes place at stated intervals, the theory being that if the intervals are short enough insufllcient metal is transferred and built up on the one contact to affect the efficiency. Exhaustive tests, however, indicate that for best results it is absolutely. essential that the polarity be reversed at each operation of the breaker arm. Even maintaining constant polarity for several operations of the breaker arm before reversal will inevitably result in a reduced eihciency. The reason for this seems to be that. the metai transferred, together with its inclusions, is in itself an inefficient conductor and that when the polarity. is reversed after a certain number of breaker arm operations. all the inclusions are not retransferred to the initial point, although part of the metal is and with it an additional quota of included matter. As a result, both points eventually become inefilcient. In some cases the damage may even be greater thanwhen points are used under constant polarity at all times.

Granting the advisability of reversal of polarity at every operation of the breaker arm, it has not heretofore been possible to obtain a mechanism which would effect this and which would'be operable and dependable in the restricted space available in the distributor structure proper. Many attempts have been made to effectuate this, but all of them suffer from the effects of either being so bulky as to require an increased over-all dis tributor dimension or to be undependable in operation. a

An advantage of this invention is that the construction disclosed by it may be disposed in the conventional distributor casing without increasing perceptibly the size thereof. Another advantage is that the structure for the reversal'of highly efficient and positive in action without being complex in structure. Another advantage is that the reversal structure is so arranged that the assembly or disassembly of the distributor is not complicated and the functions of the distributor, such as automatic adjustment with respect to engine speed or manifold pressure, are not interfered with. I 1

With these and other objects in view, the invention consists in the arrangement, construction and combination of the various parts of the im-. proved device, as. described in' the specification, claimed in the claims and illustrated in the accompanying drawings, in which:

35 Fig. 3.

Fig. 5 is a plan view of the inner face of the commutator disc as indicated by line. B-'-5 of Fig. 3.

Fig. 6 is a transverse section through the com 30 mutator disc, taken on the line 8-0 of Fig. 4.

Figure 7 is a partial elevation corresponding to Figure 1 and showing the reversing switch construction. The guards and spring arms on one side thereof have been broken away to show the arrangement of the switch. arm and the spring arms on the opposite side.

Referring to Fig. 1. a distributor substantially of usual design for a four-cylindered engine is shown, which has the case it, the breaker arm plate H mounted therein; the shaft ii; the breaker cam l3, and the breaker arm I which is mounted on the pivot post I! and has a cam follower IB and breaker arm point H. The other point I! is mounted on the breaker plate I I, and while the plate is mounted for rotational movement within a limited scope to permit automatic spark adjustments for engine characteristics in the usual manner, it may be considered, for the present, as being substantially fixed.

Also-mounted on the breaker plate ii is the double-throw, two-contact switch 20, which is pivotedin the post 2| and which has a cam follower 22 in contact with the switch cam 23 secured to the shaft It. The switch arm 24 has a polarity, in either of the embodiments shown, is 65 pair of contacts 2! on each side, which are vertically aligned, the opposite contacts being interconnected. Pairs of spring contact arms 26 are located on each side of the switch arm 24, vertically arra ged to make contact with the contacts 25 on the switch arm. These elements are so interconnected, as will be readily apparent to those working in this art, to eiIect a circuit similar to that shown in Fig. 2 so that on oscillation of the switch arm 24 in response to the switch cam 23, the contacts 25 on opposite sides alternately make and break with the respective spring contact arms 26, thereby reversing the direction of current flow to the points I! and Ill and reversing the polarity thereof intermediate each operation of the breaker arm. The spring arms 26 on each side are protected by guards 30 overlying them and rigidly secured to the abutment ll. Each guard 30 is formed with an oblique end. 32 having an aperture 33 through which extends the reduced end 34 of the corresponding spring arm 26.

Another embodiment is shown in Figs. 8 to 6, inclusive, having the case 40; the breaker plate 4|; shaft 42; the breaker cam 43, and breaker arm 44 mounted on the pivot post 45. The wiring and arrangement of the breaker arm assembly proper is similar to that shown in Fig. 1.

The reversing structure comprises a commutator disc 46 which is keyed to the shaft 42 along with the breaker cam 43, and pairs o1 brushes 4'! and 43 disposed on the outer and inner sides of the disc 46, respectively. These brushes are carried on supports 49 and 50 secured to the case 40 enclosing spring means resiliently urging the brushes 4'! and 48 into contact with opposite sides of the commutator disc 46.

The disc 45 has a base of insulating material 51 and a number of interconnected commutator segnected to the opposite continuous concentric ringsv 54 as at 56 (Fig. 6). The outer brushes 4'! are radially aligned to contact the two rows of concentrically arranged individual segments 53 while the inner brushes 48 are similarly in contact with the two continuous concentric rings 54. It will be apparent that on rotation of the disc 48, the inner brushes make continuous contact with the rings 54, while the outer brushes are alternately connected in one sense and then in the other to the inner rings as the successive individual commutator segments move under the brushes.

It will be noted that breaker cam and switch cam or commutator brush arrangement, as the case may be. are so related that the circuit for reversal is completed when the breaker arm circuit is opened; so, of course, there are no deleterious eflects due to arcing between the brushes or switch arm points. As a further example of the versatility of this arrangement, the distributor in Fig. 1 is designed for a four-cylinder engine while that in Fig. 3 is for a six-cylinder construction. One of the prime advantages of the construction is that even larger numbers of cylinders can be handled without increasing the size 4 of the reversal mechanism, and this is important when such engines as eighteen-cylindered aircraft engines are under consideration. It is possible merely by redesign of the switch cam or the commutator plate, as the case may be, to accommodate any number of reversals per cycle.

A particular value of the arrangement is that in each,embodiment the principal portion to the reversal structure, per se, is mounted on the breaker arm plate and is removable with it, while the actuating structure is secured to the distributor shaft and removable with it. As a result, the ordinary procedure in assembling and disassembling the distributor may be followed. The reversal structure itself does not unduly complicate either the operation or construction of the distributor as a whole. At the same time, the breaker arm plate may be rotated within the usual limits to vary the spark timing without affecting the reversal operation.

Some changes may be made in the arrangement, construction and combination of the various parts of the improved device without departing from the spirit of the invention and it is the intention to cover by the claims such changes as may reasonably be included within the scope thereof.

The invention claimed is:

1. In a distributor, a casing, a. shaft rotatably mounted in said casing, a plate secured to said casing, a breaker arm assembly mounted on said plate, including co-operating distributor points. a first pair of brushes mounted on said plate, a commutator disc secured to said shaft one side thereof co-operating with said brushes, a second pair of brushes aligned with said first pair and secured to said casing and co-operating with the opposite side of said commutator disc, a plurality of contacts on each face of said disc arranged in concentric spacing corresponding to the spacing between brushes constituting said pairs, electrical interconnections between the contacts on opposite sides of said disc, said connections effective to reverse the polarity of said breaker arm distributor points intermediate each operation of said breaker arm during rotation of said commutator disc.

2. In a distributor, a case, a shaft rotatably mounted in said case, a breaker arm plate secured to said case, a breaker arm assembly including co-operating distributor point mounted on said plate, a cam on said shaft effective to operate said breaker arm to make and break said distributor points, a commutator disc rotating with said shaft, aligned brush means disposed on either face of said commutator disc co-operating with contacts on opposite faces of said disc, said contacts' being arranged in two concentric rows, comprising spaced contacts on one face thereof and continuous contacts on the other face thereof, alternate contacts of said spaced contacts being directly connected to said continuous contacts on the opposite face, said other paced contacts bemg reversely connected to said continuous contacts on the other face, whereby the polarity of said breaker arm distributor points is reversed intermediate each operation of said breaker arm.

3. In a distributor, a case, a shaft rotatably mounted in said case, a plate secured to said case, a breaker arm assembly mounted on said plate and including co-operating make and break distributor points, a cam on said shaft effective to operate said breaker arm, a commutator plate of insulating material secured to and rotating with said shaft and spaced inwardly of said plate, con tacts on opposite sides of said plate comprising each a pair of concentrically arranged contacts,

the contacts on one side of said plate being in the form of continuous rings, the contacts on the other side of said plate being spaced segments,

alternately spaced segments being directly con-' nected to the opposite continuous rings, the other spaced segments being reversely connected to said ccntinuous'rlngs on the opposite side of the plate, a plurality of axiallyaligned brush means se- 6 cured to said plate and said casing on opposite sides of said commutator disc co-operating with said commutator contacts and eiiective on rotation of said shaft to reverse the direction 0! current now through said breaker arm distributor points intermediate each operation of said breaker arm.

HENRY FORD. EMIL ZOERLm. 

